Fluid-rheostat.



M. N. scn'duwnz. FLUID RHEOSTAT.

APPLICATION FILED JUNE 261 i916.

1,256,832, Patmted Feb.19,1918

2 SHEETS-SHEET A 'TTORNE Y M. N. scu'dmwnz.

FLUID RHEOSTAT.

APPLICATION FILED JUHEZB. 191s.

"@QQ/M J A TTORZVE Y UNITED STATES PATENT OFFICE.

MICHAEL N. SCHi'lNWITZ, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO THE CUTLER- I-IAMMER MFG. C0,, 0F MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

FLUID-RI-IEOSTAT.

Specification of Letters Patent.

Patented Feb. 19, 1918.

Application filed June 26, 1916. Serial No. 105,825.

To all whom it may concern:

Be it known that I, MICHAEL N. SCI-[6N- WITZ, a subject of the Emperor of Germany, residing at Milwaukee, in the county of Milwaukee and State of \Visconsin, have invented new and useful Improvements in Fluid-Rheostats, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a. part of this specification.

This invention relates to rheostats and more particularly to those of the fluid or electrolytic type.

The invention has among its objects to provide in a rheostat of the character stated means for insuring substantial equality of the resistances between the various phases of a polyphase current.

A further object is to provide a fluid rheostat in which the flow of current is uniform between corresponding portions of the electrode surface throughout the range of regulation.

A further object is to minimize the production of stray currents and the corrosive action incident thereto.

A still further object is that of equalizing the circulation and cooling efiect of the electrolyte in a rheostat of the type stated.

Other objects will appear as the descrip tion proceeds.

In the accompanying drawing, wherein is illustrated an embodiment of the invention,

Figure 1 is a vertical section thereof;

Fig. 2 is a top plan view, while,

Fig. 3 is a horizontal section on line 33, Fig. 1.

Referring to the drawing and more particularly to Fig. 1, the rheostat comprises aseries of fixed electrodes 1 operating in conjunction with an equal number of movable electrodes 2 both sets of electrodes being inclosed within a circular tank 3 to be gradually filled with fluid, together with means for varying the distance between the two series of electrodes.

An outer or overflow tank 4 surrounds the aforesaid electrode tank and is provided with a horizontal flange 5 which serves as a support for said inner tank to maintain the same at a substantial distance above the bottom of said overflow tank and concentric therewith. Said overflow tank is further provided at its top with a cover plate 6, said cover plate having a relatively large central opening 7 and a circular series of smaller openings 8 surrounding the same and equally spaced in pairs. Said tanks may be of any suitable or desirable material, either conductive or non-conductive.

A series of conductive bolts 9 surrounded by insulating sleeves 10 project through the smaller openings in the cover plate 6, said bolts constituting supporting means for the fixed electrodes.

The fixed electrodes 1 are of like construction and each comprises a tapered section or casting of suitable conductive material, V-shaped in cross section, as shown in Fig. 3, and having at its broader end a pair of upstanding and outwardly bent supporting lugs 11 adapted for connection with the inner ends of the conductive bolts 9, the bolts and lugs serving jointly as supporting and conductive means for the said electrodes. The electrodes are thus inverted and arranged symmetrically about a common axis with their closed or V-pointed portions posi tioned as elements of a conical surface and their edge portions lying in vertical planes.

In order to equalize the resistance between different phases of a polyphase current, each phase of said current is connected with a pair of diametrically opposed electrodes whereby twice as many electrodes as current phases are required. The above stated connection is effected by means of bus-bars 12 each of which is provided with an engaging terminal for the wire of its particular phase and is in circuit with a pair of diametrically opposed electrodes by being attached to the outer ends of the appropriate conductive bolts 9.

The movable electrodes 2 constitute the star or neutral point of the resistance and are grounded through their common supporting means. Their form is in general similar to that of the fixed electrodes hereinbefore described, each being substantially V-shaped in cross section to conform to the contour of the fixed electrodes with which the former are adapted to cooperate, the angle and proportions of the two sets being similar. The said movable electrodes are mounted upon a star or spider 13 so that the various active surfaces thereof are maintained parallel to and equidistant from the corresponding surfaces of the fixed electrodes. The spider 13 is slidably mounted upon a vertical rod 1 1 which is centrally suspended from the cover plate 6 by means of braces 15 extending within and across the opening '7 therein, said rod extending downwardly within the electrode tank 3. A pair of links 16 serve to connect the central sleeve of the spider with an operating lever 17 pivoted at 18 upon a support carried by the outer tank cover 6 while a counterweight .19 serves to compensate the weight of said movable electrodes.

Owing to the similar contour and parallel arrang: :-ment of the fixed and movable electrodes above described, it is obvious that as the movable electrodes are raised the active surfaces thereof approach the corresponding surfaces of the fixed electrodes and further, that said cooperating surfaces will remain parallel with each other irrespective of the relative vertical position of the electrodes. It is also obvious that the distance between said coacting surfaces which decreases as the movable electrodes are raised,

' is the same between all portions of said coacting surfaces whereby an even distribution of current is at all times insured.

The electrolyte tank 3 is provided at its bottom with a centrally located circular weir 20 while an oscillatory valve 21 mounted upon a spindle 22 serves to close the bottom of said weir. The said spindle projects laterally outside the overflow tank and terminates in a weighted lever 23 whereby said valve may be actuated.

For producing a flow of electrolyte upwardly from the overflow tank into the electrode tank, a pipe is connected at 245 with said overflow tank and communicates through a suitable pumping means (not shown) with the interior of the electrode tank. For insuring uniform delivery of electrolyte to all parts of the electrode tank the supply pipe 25 terminates in a perforated annulus 26 surrounding the weir 20, while a diffusion apron 27 surrounds said annulus for further equalizing the inflow of electrolyte.

The supporting rod for the movable electrodes is itself supported at the lower end thereof by a spider 28 riveted to the interior of the we'r 20.

Obviously the upper periphery of the electrode tank 3 and the top of the weir 20 serve respectively as upper and lower limits to the height of electrolyte within said tank. The fixed electrodes 1, moreover, are mounted at such a heightwithin the aforesaid tank that their tips are at all times immersed in the electrolyte retained therein by the weir, whereby a circuitthrough the said electrodes is insured. The resistance, however, under these conditions is the maximum.

The operation of the above described rheostat, for example, in starting a motor and bringing the same up to speed, may be described as follows: A low initial current being desired the valve 21 is first opened permitting the electrolyte to descend into the overflow tank down to the level of the top of the weir 2O whereupon the motor circuit may be closed, the resistance of the rheostat being high. It being thereafter neces sary to reduce said resistance the valve 21 is closed while the pumping means operates to raise the level of the electrolyte in the electrode tank. As said electrolyte rises the active surface of the fixed electrodes is increased. Moreover, more closely adjacent portions of such surfaces are rendered ac tive, thus decreasing the resistance to the passage of current, which u continues until the electrolyte reaches the top of the tank 3 thus rendering the entire conductive surface of the fixed electrodes active for transmitting current. Thereafter the electrodesimply overflows into the overflow tank, this being the condition of minimum resistance attainable by said means.

Further reduction of the resistance is at tained by reducing the distance between the fixed and movable electrodes. By actuation of the lever 17 the movable electroc es are lifted and caused to approach the fixed electrodes thereby shortening the patl. through the electrolyte which the current must traverse. This reduction may continue until the two sets of electrodes are practically in contact thereby virtually short-circuiting the rheostat.

Owing to the particular formation of the fixed electrodes and their arrangement with. only their tips first immersed in the electrolyte the initial reduction in the resistance due to the rise of electrolyte will be relatively slow owing to the slow increase in the submerged surface of the said electrodes. is the electrolyte rises higher thercabout, however, the ratio of the active area to the depth of the electrolyte increases rapidly, thus producing a correspondingly rapid re sistance reduction.

The above described arrangement of electrodes furthermore permits the space between said electrodes awl e oiniding tank to be relatively small, even when said tank is composed of conductive material, the tendency of the current to pass from said electrodes to said tank being relatively slight as the path of least resistance for said current is between adjacent fixed and movable electrodes.

The course followed by the electrolyte upon leaving the perforated annulus 26 is particularly advantageous. Leaving said annulus the electrolyte passes the diffusion apron 27.and thence flows about and between the fixed and movable electrodes and rises'by reason of the pressure of the pumping means and also by reason of the heat generated by the passage of current therethrough. By the above described circulation of the electrolyte the electrodes are effectively cooled and furthermore their surfaces are effectively scoured and scrubbed for the removal of all gas bubbles and other products of the corrosive action of said current. Owing to the circular character of the diffusion apron 27 and of the overflow from the top of tank 3 the circulation of the electrolyte is practically uniform throughout the rheostat, it being further noted that the movable electrodes are at all times substantially submerged in the electrolyte thereby preventing undue current concentration over mall areas adjacent their tips,

hat I claim as new and desire to secure by ettcrs Patent is:

1. In a fluid rheostat, in combination, an electrolyte tank, a series of electrodes mounted therein. for uninterrupted contact With said electrolyte and arranged symmetrically about a given point with their adjacent conductive faces parallel in all horizontal sections, said electrodes being ta ered whereby upon a rise of the electrolyte thereabout the active surface of said electr des increases more rapidly than the height of said electrolyte.

In a fluid rheostat, in combination, a symmetrically arranged series of electrodes having their adjacent conductive faces parallel in transverse section, and a series of similarly arranged electrodes movable as a unit With respect to said first mentioned electrodes.

3. In a fluid rheostat, in combination, a symmetrically arranged series of electrodes having their adjacent conductive faces parallel in horizontal section and a series of similarly arranged electrodes movable as a unit with respect to said first mentioned electrodes, the adjacent surfaces of said respective sets of electrodes being at all times parallel.

t. In a fluid rheostat, in combination, a plurality of symmetrically arranged fixed electrodes having their adjacent conductive faces parallel in cross section, and a series of similarly arranged electrodes mova is as a unit with respect to said fixed electrodes, the adjacent surfaces of said fixed and movable electrodes being at all times parallel and substantially uniformly spaced at all points.

5. In a fluid rheostat, in combination, a tank containing an electrolyte, means for varying the level of said electrolyte, a plurality of symmetrically arranged electrodes having their adjacent surfaces parallel in cross section mounted permanently in contact with said electrolyte, and a series of similarly arranged electrodes substantially immersed in said electrolyte and movable as a unit therein with respect to said first mentioned electrodes for varying the distance between adjacent surfaces of said sets of electrodes while maintaining said surfaces at all times parallel.

6. In a. fluid rheostat, a circular electrolyte tank containing stationary and movable electrodes, means for admitting electrolyte to said tank and discharging electrolyte therefrom, said admission and discharge means being arranged concentric With said tank to insure uniform distribution of electrolyte therein.

7. In a fluid rheostat, an electrolyte tank, means for admitting electrolyte to and discharging the same from said tank to vary the height of electrolyte therein While in suring a circulation of electrolyte, and a series of stationary and movable electrodes in said tank in the path of said circulating electrolyte to be scrubbed and secured thereby.

8. In a fluid rheostat, in combination, a tank, an electrolyte to be circulated therethrough, and a. plurality of stationary and movable electrodes arranged symmetrically to the path of circulation of said electrolyte.

9. In a fluid rheostat for polyphase currents, in combination, a tank containing electrolyte and a plurality of electrodes mounted Within said tank, said electrodes being circuit connected in pairs corresponding with the respective current phases and the electrodes of each pair being disposed adjacent to opposite sides of said tank.

10. In a fluid rheostat for polyphase currents, in combination, an electrolyte tank and a plurality of electrodes symmetrically arranged therevvithin, the conductive surface for the various current phases being divided into pairs of diametrically opposed electrodes for equalizing the said phases.

11. In a fluid rheostat, a longitudinally tapered electrode V-shaped in transverse section.

In a fluid rheostat, a longitudinally tapered electrode J-shaped in transverse section having at one end a combined supporting and terminal lug.

13. In a fluid rheostat, a symmetrical series of longitudinally tapered electrodes V-shaped in transverse section, mounted to maintain the surfaces of each electrode parallel to the adjacent electrode surface at all points along said section.

i l. In a fluid rheostat, in combination, an electrolyte, a symmetrically arranged series of electrodes having their adjacent conductive surfaces parallel in transverse section, and a series of similarly arranged electrodes movable as a unit with respect to said first mentioned electrodes, said movable electrodes being at all times substantially submerged in said electrolyte.

15. In a fluid rheostat, in combination, an electrolyte, a series of electrodes mounted for submersion therein, a second series of electrodes movable vertically with respect to said first mentioned series and arranged to be at all times substantially submerged in -aid electrolyte.

16. In a fluid rheostat, in combination, a circular tank, a symmetrical series of electrodes mounted concentrically therein to present relatively large areas toward each other and relatively small areas in proximity to said tank.

17. In. a fluid rheostat, in combination, a circular tank, a symmetrical series of electrodes mounted concentrically therein to present relatively large areas toward each other and relatively small areas in proximity to said tank and a plurality of substantially submerged electrodes arranged "centrally of said first mentioned series of electrodes for the purpose set forth.

18. In a fluid rheostat, in combination, a symmetrically arranged series of fixed electrod s having their adjacent conductive faces parallel in transverse section, and a series of similarly arranged electrodes movable as a unit with respect to said fixed electrodes, the corresponding phases of said lined and movable electrodes being at all times parallel.

In witness whereof, I have hereunto subscribed my name.

n. SCHONWITZ.

Copies or this patent may "so obtained for five cents each, by addressing the Commissioner of Eatcnts,

Washington, D. G, 

